E. F. Litvin

Catalytic peoperties of palladium. Fixed on poly(m- and p-) hydroxyphenylbenzoxazole-terephthalamides

ConclusionPolymeric chelates of palladium with poly(m- and p-)hydroxyphenylbenzoxazoleterephthalamides as fibers exhibit catalytic activity in the hydrogenation of monoolefins and dienes.

Investigation of the catalytic reduction of p-nitrobenzoic acid and its salts on Pd-, Rh-, and Ru-catalysts

1. The reduction of the nitro group of p-nitrobenzoic acid and its salts on Pd-, Ru-, and Rh-catalysts is zero order with respect to the substrate, first order with respect to hydrogen, and is not inhibited by the reaction product. 2. The activity of the catalysts in the reduction of the nitro group decreases in the series Pd≫Rh> Ru, while in the case of hydrogenation of the aromatic ring it decreases in the series Rh≥Ru≫Pd. 3. The optimum condition of the catalytic synthesis of p-aminobenzoic acid are: 0.5% Pd/C, 90–120‡, 30 atm, aqueous suspension.

Selectivity of the catalytic reduction of terephthalyl dichloride to terephthalaldehyde

Conclusions1.The catalytic reduction of terephthalyl dichloride over Pd/C to terephthalaldehyde is zero order with respect to substrate and first order with respect to hydrogen, and has low selectivity.2.The activity of supported catalysts in the reduction of the acid chloride group increases in the sequence Pt < Rh < Ru ≪ Pd. In aldehyde hydrogenation the sequence is Rh < Ru < Pt ≤ Pd.3.The reduction of terephthalyl dichloride proceeds by a stepwise mechanism. The selectivity is determined by the ratio of the hydrogenolysis rate of the C-Cl bonds of the acid chloride to the hydrogenation rate of the C(O)H group.4.Palladium supported on activated carbon in the presence of modifiers containing nitrogen or sulfur is the best catalyst for the reduction of terephthalyl dichloride to terephthalaldehyde.

Selectivity and stereoselectivity of the hydrogenation of diphenylacetylene in the presence of group VIII metal catalysts

Conclusions1.In the presence of both heterogeneous and homogeneous Group VIII metal catalysts the hydrogenation of diphenylacetylene proceeds stepwise. At the stage of addition of 1 mole of H2, the main product is cis-stilbene; diphenylethane and trans-stilbene are also formed. Pd/CaCO3 modified with lead acetate and quinoline and the [PtCl2(SnCl3)2]2− complex are the most selective and stereospecific. Rh black and the Py3RhCl3-NaBH4, are the least selective.2.The reduction in the selectivity of stilbene formation at the stage of addition of 1 mole of H2 is due to its concurrent hydrogenation. The selectivity can be increased by the addition of an “adsorptive-displacing” component (pyridine, quinoline).3.Conversion of cis-stilbene to the trans form is accompanied by hydrogenation. For this reaction, Ru-C and the Py3RhCl3-NaBH4 are the most active.

Catalytic properties of blue ruthenium complexes

1. A simple method was developed for obtaining the blue solution of Ru chloride complexes by the reduction of Ru(IV) compounds with hydrogen in the presence of Ru black. 2. The Ru chloride complexes accelerate a migration of the C=C bond and the cis-trans isomerization of olefins, without catalyzing their hydrogenation. 3. The described complexes catalyze the selective hydrogenation and isomerization of dienes.

Hydrogenation of stable nitroxyl radicals with acetylenic bonds on Ni, Pd, and Pt catalysts

Conclusions1.We have examined the liquid-phase hydrogenation of stable iminoxyl radicals with acetylenic bonds — 4-ethynyl-4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl and 4-phenylethylnyl-4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl on Raney Ni, Pt, and Pd catalysts.2.On Raney Ni the paramagnetic center and the C=C bond of the radicals are reduced simultaneously; in the presence of Pt the iminoxyl group is preferentially hydrogenated, while on Pd black the C≡C bond is reduced (via the olefinic compound) without affecting the paramagnetic center.3.In the course of this work we have prepared several new stable iminoxyl radicals: 4-ethynyl-4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl and 4-phenylethynyl-4-hydroxy-2,2, 6,6-tetramethylpiperidin-1-oxyl, 4-vinyl-4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl, 4-(5-phenylvinyl)-4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl, and 4-(β-phenylethy1)-4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl, together with 4-vinyl-1,4-dihydroxy-2,2,6,6-tetramethylpiperidine and 4-ethyl-1,4-dihydroxy-2,2,6,6-tetramethylpiperidine.

Preparation and properties of ruthenium catalysts for the liquid-phase hydrogenation of aromatic compounds

Conclusions1.The specific surface of ruthenium and its activity increase as a function of the nature of the support as follows: Ru/SiO2<Ru/γ-Al2O3<Ru/C. The specific activity (per m2 of surface) is practically independent of the composition of the support and method of hydrogenation.2.The catalyst obtained by the sorption of ruthenium hydroxytrichloride onto carbon at pH 5.9–6.1 and reduced with hydrogen (300‡C) or NaBH4, (20‡C) possesses higher dispersity and weight specific activity during the hydrogenation of ammonium p-aminobenzoate than the catalyst prepared by reported methods.3.The effectiveness of the catalyst developed was confirmed by experiments on the hydrogenation of aromatic acids and acenaphthene. The expected products were obtained with an 86–98% yield.

Catalytic hydrogenation of disubstituted benzenes and configurational isomerization of the corresponding cyclohexanes. 6. Configurational isomerization of substituted cyclohexylamines and cyclohexanols on Ru-Al2O3

Conclusions1.In aqueous solutions in the presence of hydrogen ruthenium on aluminum oxide catalyzes the configurational isomerization of alkyl- and alkoxycyclohexylamines and amino- and alkylcyclohexanols. Isomerization is not observed in an inert gas atmosphere.2.The reaction rate decreases with increase in the size of the alkyl substituent and depends on the nature of the substituent and on its position in the cyclohexane ring. NAcetylmethylcyclohexylamines do not isomerize.3.In the absence of a solvent and also in solution in ethanol, dioxane, acetic acid, or alkali isomerization of substituted cyclohexylamines and cyclohexanols is not observed.

Linear oligomerization of 1,3-pentadiene in presence of catalytic system CoCl2-PPh3-NaBH4

The system CoCl2-PPh32-NaBH4 catalyzes the oligomerization of trans-1,3-pentadiene to 4-methyl-2,5,7-nonatriene and the 1,3-pentadiene trimer. 4-Methyl-2,5,7-nonatriene is formed predominantly at 95°, while the trimer is the predominant product at 120°. This system does not catalyze the oligomerization of cis-1,3-pentadiene.

Preparation, stabilization, and catalytic activity of a supported palladium chlorodimethyl sulfoxide complex

1. Polyvinylpyrrolidone stabilizes the reduced NaBH4 homogeneous Pd chlorodimethyl sulfoxide catalyst in hydrogenation and isomerization reactions. 2. A method has been developed for preparing and stabilizing Pd chlorodimethyl sulfoxide catalysts through treatment with N-polyvinylpyrrolidone. 3. The Pd complex, rather than the metallic palladium, is responsible for the activity of the supported catalyst in the reactions studied here.